Web materials having three-dimensional surfaces are well known in the art and have been utilized in many different applications. Such web materials may be made in planar web form and remain in that form throughout handling or they may be made in continuous web form and be wound on rolls for handling. An exemplary three-dimensional web material, as well as methods and apparatus for manufacturing same, is disclosed in U.S. Pat. No. 5,662,758. An exemplary method for providing amorphous embossing patterns upon a web material is described in U.S. Pat. No. 6,254,965.
Accordingly, it would be desirable to provide a manipulated amorphous structure for a formed web material so that randomness is preserved yet desired structural properties can be designed into the material. Unlike array patterns, an amorphous pattern eliminates linearity and pattern repetition in the web material, providing for macro scale uniform appearance. The amorphous pattern provides maximum space utilization which is preferred for building caliper and drying the web material. Elongating the amorphous pattern in a given direction while maintaining equal overall pattern area allows the modulus (i.e., slope of the load vs. elongation curve) of the web material to be increased or decreased while still preserving the characteristics of the amorphous pattern.
A web material run through a constant depth deformation device, such as an embosser, will undergo elongation deformation. If the emboss impression is to remain in the web material after the embosser disengages, the web must be elongated to the yield point during embossing. A lower modulus material will by definition elongate a greater amount than a higher modulus material with equal tensile strength. If the amount of elongation of the web material becomes too great, and the elongated substrate is constrained by repeating, co-linear emboss groupings, the elongated substrate will buckle and form a hump of elongated material beyond the plane of the local material. Furthermore, regardless of emboss design, a lower modulus, equal tensile substrate will require greater embosser engagement (material elongation) to reach the yield point. Thus, a higher modulus material is preferable because it elongates less, requiring less engagement of emboss pins to reach permanent deformation (and permanent emboss) and creating less buckling within a constrained area.
Accordingly, in order to overcome these issues, it would be desirable to provide a web material having an amorphous pattern comprising elongate two-dimensional geometrical shapes disposed thereon. Further, it would be desirable to provide a method for forming such web materials having an amorphous pattern comprising elongate two-dimensional geometrical shapes which may be suitably tailored for a particular material need and which may be readily and economically practiced.